Carbon forms a large number of nanostructures, for example, nanotubes, buckyballs, nanopaper, buckypaper, bundles, graphene, etc. Typically, carbon nanotubes exhibit unique mechanical properties, for example, high strength and ductility. Carbon nanotubes possess a Young's modulus in the order of, for example, about 270 gigapascal (GPa) to about 950 GPa, and a tensile strength of, for example, about 11 GPa to about 63 GPa. The radial mechanical properties of carbon nanotubes are generally inadequate and carbon nanotubes do not perform well under compression compared to when the carbon nanotubes are under tension because of their structural anisotropy and hollow cores. Since production of substantially long carbon nanotubes is difficult, carbon nanotubes are typically mixed with other materials to form composites, or are agglomerated into bundles, or are made into buckypaper to make the carbon nanotubes amenable for macroscale applications. In composites, inadequate adhesion of the carbon nanotubes to a matrix material results in substandard performance of the composites. The weak bonding of adjacent carbon nanotubes in bundles and buckypaper nanostructures limits the strength of the bundles and the buckypaper nanostructures.
Similarly, multi-walled carbon nanotubes with few bonding sites possess less wall-to-wall adhesion, causing super lubricity which leads to outer walls of the multi-walled carbon nanotubes bearing the majority of any mechanical loading on the multi-walled carbon nanotubes. Mechanical loading on the multi-walled carbon nanotubes relates to compression, or tension, or torsion, or bending, or any combination thereof, on the multi-walled carbon nanotubes. To resolve the issue of less wall-to-wall adhesion, functional groups are added to the carbon nanotubes or radiation is used to induce defects in the carbon nanotubes after the production of the carbon nanotubes. The induced defects in the carbon nanotubes help to bond adjacent walls and nanotubes in the multi-walled carbon nanotubes. While improving adhesion, functionalizing these carbon structures is detrimental to the intrinsic mechanical properties of the carbon structures. The process of adding a functional group to the carbon nanotubes after the production of the carbon nanotubes is referred to as functionalization. In general, for a multi-walled nanostructure, enhanced wall-to-wall adhesion improves mechanical properties of the multi-walled nanostructure.
Carbon nanotubes, in general, are either semiconducting or conducting. There is a need for carbon nanotubes with enhanced insulation properties for certain applications, for example, energy storage or electrical shielding. For applications that involve, for example, energy storage or electrical shielding, there is a need for a material with similar dimensions and mechanical properties as that of carbon nanotubes. Radiation shielding is required in multiple applications, for example, aerospace applications, nuclear applications, etc. In general, carbon nanotubes are poor in shielding certain types of radiation, for example, gamma radiation, X-radiation, ultraviolet radiation, etc. If enriched boron or depleted boron can be added to carbon nanotubes, the carbon nanotubes can be enhanced to provide protection against harmful radiation. Enhanced adhesion to matrix materials in composites of carbon nanotubes creates multiple applications for composites of carbon nanotubes. Typically, carbon nanotubes are functionalized to provide additional functionality to the carbon nanotubes by providing a path for tailoring properties of the carbon nanotubes. However, carbon nanotubes are difficult to functionalize and the functionalization only occurs at defect sites in the structure of the carbon nanotubes. If more functionalization sites are added to the carbon nanotube structure, most likely, more types and more effective functionalization will result.
Hence, there is a long felt need for a method for producing boron filled hybrid nanotubes that are insulating, exhibit enhanced mechanical properties, thermal properties, and electrical properties, can be effectively functionalized, and provide radiation shielding. Moreover, there is a need for a boron filled hybrid nanotube that exhibits enhanced adhesion to matrix materials in composites. Furthermore, there is a need for a boron filled hybrid nanotube that possesses a corrugated structure that allows mechanical loading to be transferred from the outer walls of the boron filled hybrid nanotube to the inner walls of the boron filled hybrid nanotube, and thereafter to a boron filled core of the boron filled hybrid nanotube.